House Oversight and Government Reform Committee Chairman Darrell Issa has asked former Health and Human Services Secretary Kathleen Sebelius and former Labor Secretary Hilda Solis to appear before his committee as part of an ongoing investigation into potential misuse of taxpayer funds for political purposes, according to Politico.

Issa is investigating whether the Obama administration, in particular the White House Office of Political Strategy and Outreach (OPSO), has violated the Hatch Act, a law designed to prevent taxpayer dollars from being used to fund political activities by government workers.

The invitation comes days after Issa issued subpoenas seeking documents "related to the reopening of the White House political office after two members of President [Barack] Obama’s Cabinet [Sebelius and Solis] were found to have violated laws intended to prevent the abuse of taxpayer dollars for partisan political efforts," according to a committee release.

Federal Bureau of Investigation (FBI) agents interviewed Solis about her involvement in a 2012 fundraiser for the Obama re-election campaign, according to a February report in the Los Angeles Times.

Solis, who is a candidate for Los Angeles supervisor, had "cordial" talks about her attendance at an event held at the La Fonda supper club in Los Angeles, said Steve Barkan, her campaign adviser.

The event was thrown by the Latino community to support Obama’s re-election. The federal Hatch Act bans Cabinet members from directly raising campaign money, although they are approved to give speeches at fundraisers.

The Office of Special Counsel issued a September 2012 report, which found that Sebelius "violated the Hatch Act when she made extemporaneous partisan remarks in a speech delivered in her official capacity on February 25, 2012."

After the event, her trip was reclassified by the Health and Human Services Department from official to political and issued a statement to that effect. The Democratic National Committee reimbursed the U.S. Treasury for all costs and expenses associated with her travel, the report stated.

The August subpoenas are more limited in scope than a similar set of requests sent in March, but both subpoenas pertain to an ongoing investigation into whether the office violated the Hatch Act.

Specifically, the March subpoenas were seeking information concerning a June trip to Minnesota and a July trip to Colorado that were described as official stops, but during which Obama attended several political fundraisers.

A White House spokesman said the documents would be handed over to the committee this week.

"We’ve been extremely forthcoming in response to the committee’s requests on the Office of Political Strategy and Outreach, including briefing the chairman’s office, providing responsive documents and providing additional information in letters to the committee," the spokesperson told Politico.

The OPSO was created in 2009, but was closed two years later to allow for those staff members to focus on Obama's re-election campaign. In 2011, it was reopened to enable the administration to react more efficiently to political requests, officials told The New York Times.

Issa also contacted Carolyn Lerner at OSC seeking information regarding the involvement of former Secretary of Labor Hilda Solis at a fundraiser for Obama's re-election campaign.